1. Technical Field
The present invention relates to wireless communication networks, and more particularly, a method and apparatus for managing a supplement data channel in a Code Division Multiple Access network.
2. Description of the Related Art
Wireless networks, and more particularly, Code Division Multiple Access (CDMA) networks are being modified in a manner consistent with standard IS-2000. One change that is defined in the IS-2000 standard for next generation CDMA networks is the addition of a supplemental channel. Heretofore, only a fundamental channel was used to transmit data in IS-95 systems. Now, however, a supplemental channel has been defined for transmitting large blocks of data on an as needed basis. In the past, IS-95 has been used for carrying voice traffic.
Next generation systems, however, are being designed to also carry data traffic. Accordingly, the IS-2000 CDMA standards define a supplemental channel that can carry in excess of 300 kilobits per second. In contrast, a traditional voice channel only carries 9.6 kilobits per second.
As CDMA is becoming the preferred platform for next generation systems, and more particularly, for transmitting large amounts of data over a wireless link, new system issues are being presented, or alternatively, are being presented in newer and more challenging ways. For example, power control has always been a key part of a system designed for a CDMA system. A goal in power control for CDMA systems is to minimize the power transmission level that is required to deliver data with a specified signal quality or error rate. For example, voice data is usually expected to be delivered with a 1% frame error rate. Thus, if the frame error rate is below 1%, the power transmission level is reduced. In contrast, if the received frame error rate exceeds 1%, then the power transmission level is increased.
Because CDMA systems all transmit at the same frequency, it is important to reduce the power transmission levels so as to minimize interference to other signals. Thus, by finding the minimum transmission level for each signal, the system capacity is maximized. An additional aspect about power control, however, which becomes especially prevalent in next generation systems, is that of power capacity by the base station transceiver system.
As supplemental channel transmissions occur, the transmission power that is required to be produced by the base station for delivering communication signals to potentially hundreds of mobile stations as well as supplemental channel transmissions to a much smaller number of mobile terminals or stations, may readily require the complete power capacity of the base station transceiver system (BTS). Thus, in addition to minimizing the interference to other signals, issues exist about how and when to admit calls requiring transmissions over the supplemental channel.
A system designer of a next generation CDMA system must not only account for these factors, but also the general desire by the service providers to maximize revenue and the number of users. Accordingly, technical tradeoffs that achieve technical goals but that also maximize revenue are desirable. What is needed, therefore, is a system design for implementing a supplemental channel in an IS-2000 CDMA network that addresses each of these aforementioned concerns.